Telecommunications terms starting with E

405 terms

erlang A dimensionless unit of the average traffic intensity (occupancy) of a facility during a period of time, usually a busy hour.
erroneous block A block in which there are one or more erroneous bits.
error Error The difference between a measured value of a quantity and its true value. Different types of errors are inherent to observations.
error blocks In video, a form of block distortion where one or more blocks in the image bear no resemblance to the current or previous scene and often contrast greatly…
error budget The bit-error-ratio requirement allocated to the respective segments of a communications system, such as trunking, switching, access, and terminal…
error burst A contiguous sequence of symbols, received over a data transmission channel, such that the first and last symbols are in error and there exists no…
error concealment In the receipt and processing of digitized television transmissions, a method of covering up errors from dropouts by using the redundancy in most…
error control Any technique that will detect or correct errors.
error correction In the reception or processing of digital data, the use of overhead bits and appropriate algorithms to detect, and within certain constraints, restore a…
error message In a computer or communications system, a message that indicates that an error has been made and, sometimes, the nature or type of error. [From Weik '89]
Error Rate the frequency at which one deviates or strays from a correct standard.
error ratio The ratio of the number of bits, elements, characters, or blocks incorrectly received to the total number of bits, elements, characters, or blocks sent…
error signal In computer and communications systems, an audio or visual signal that indicates that an error has been made by the system or its operator.
error-correcting code A code in which each telegraph or data signal conforms to specific rules of construction so that departures from this construction in the received signal…
error-correcting system In digital data transmission, a system employing either forward error correction (FEC) or automatic repeat-request (ARQ) techniques such that most…
error-detecting code A code in which each telegraph or data signal conforms to specific rules of construction, so that departures from this construction in the received signal…
error-detecting system A system employing an error-detecting code and so arranged that any signal detected as being in error is either deleted from the data delivered to the…
error-detecting-and-feedback system Synonym ARQ.
error-free second (EFS) A 1-yysecond interval in which no errored blocks are received. Note: In general, measurement is over time and is stated as a percentage, i.e., % EFS. [T1.
errored second (ES) A 1-yysecond period with one or more errored blocks. 2. A 1-second interval with one or more bit errors.
errored unit of time A specified period of time, during which bits are transferred from a source to a destination, that contains at least one bit in error.
ES Abbreviation for end system, expert system.
ESC Electronic System Center (AFMC), Hanscom AFB, MA.
escape character (ESC) In alphabet coding schemes, a specially designated character, the occurrence of which in the data signifies that one or more of the characters to follow…
escape code An indicator consisting of one or more digits which is defined in a given numbering plan and is used to indicate that the digits that follow are from a…
ESD Examination Support Document -- see Guidelines for Examination Support Document (ESD) under § 1.265 [PDF]
ESF Abbreviation for extended superframe.
ESM (1) Electronic Warfare Support Measures. (2) Electronic Support Measures.
ESS Abbreviation for electronic switching system.
essential service A network-provided service feature in which a priority dial tone is furnished. Note 1: Essential service is typically provided to fewer than 10 % of…
ETB Abbreviation for end-of-transmission-block character.
Ethernet A common way of networking PCs to create a LAN.
ETX Abbreviation for end-of-text character.
evaluation See appraisal.
evaluation assurance level (EAL) One of seven increasingly rigorous packages of assurance requirements from CC (Common Criteria) Part 3.
evaluation baseline Documentation that formally defines the security functions of a system or product against which its evaluation is performed [CESG].
evaluation observation report (EOR) Report issued by a CLEF to report any problem, other than those already covered by an SFN, relating to the Target of Evaluation (TOE).
evaluation unit An organization working directly for CESG whose purpose is to perform evaluations [CESG].
Evaluator left
evaluator actions A component of the evaluation criteria for a particular phase or aspect of evaluation, identifying what the evaluator must do to check the information…
evanescent field In a waveguide, a time-varying field having an amplitude that decreases monotonically as a function of transverse radial distance from the waveguide, but…
evanescent mode A mode of the evanescent field.
even parity See parity, parity check.
event In LotusScript, an action or occurrence to which an application responds. That action can be a user-generated one, such as a mouse click; a…
EW (1) Electronic Warfare. (2) Early Warning.
exalted-carrier reception A method of receiving either amplitude- or phase-modulated signals in which method the carrier is separated from the sidebands, filtered and amplified…
exception condition In data transmission, the condition assumed by a device when it receives a command that it cannot execute.
excess insertion loss Deprecated term. See insertion loss. Note: Excess insertion loss was used to indicate that, in an optical-fiber coupler, the loss occasioned by dividing…
Exchange An exchange generally occurs when one company acquires another. The shareholders of the acquired company are often given the option to sell their shares…
exchange access In telephone networks, access in which exchange services are provided for originating or terminating interexchange telecommunications within the exchange…
exchange area A geographic area served by one or more central offices within which local telephone service is furnished under regulation.
exchange authentication information (exchange AI) [10181-2] Information exchanged between a claimant and a verifier during the process of authenticating a principal.
exchange carrier (EC) 1. A carrier authorized to provide telecommunication services within one or more access service areas. [T1.104-1988] 2.
exchange facilities The facilities included within a local access and transport area.
exchange line Synonym subscriber line.
exchange transmission plant This is a combination of (a) exchange cable and wire facilities (b) exchange central office circuit equipment, including associated land and buildings and…
exe (or .exe) 1. A filename extension identifying executable code. 2. An identifying extension for a form of self-extracting archive. [Bahorsky]
executive program Synonym supervisory program.
executive state One of several states in which an information system (IS) may operate, and the only one in which certain privileged instructions may be executed.
exempted addressee An organization, activity, or person included in the collective address group of a message and deemed by the message originator as having no need for the…
exercise key [A] key used exclusively to safeguard communications transmitted over the air during military or organized civil training exercises. [INFOSEC-99]
exhaustive attack A trial-and-error attempt to violate computer security by systematically attempting to use a very large number of possible passwords or keys.
existing quality television Synonym [in ITU-T usage] distribution-quality television.
expander A device that restores the dynamic range of a compressed signal to its original dynamic range.
Expansion The increase in volume of a soil mass.
expansion capability The inherent limit for increasing the capacity of a system beyond its installed capacity.
Expected Measured Loss (EML) The term "Expected Measured Loss" denotes a calculated loss which specifies the end-to-end 1004-Hz loss on a terminated test connection between two…
expedited data unit In layered systems, a service data unit that is delivered to a peer entity in the destination open system before the delivery of any subsequent service…
experimental station A station utilizing radio waves in experiments with a view to the development of science or technique. This definition does not include amateur stations.
expert system (ES) A computer system that facilitates solving problems in a given field or application by drawing inference from a knowledge base developed from human…
explicit congestion message A message generated by the network and sent to the user terminal to indicate a congestion condition. [T1.615-1992]
explicit services Services that can be accessed from an application program, via an API, and are generally provided only when requested [POSIX.0].
exploder Synonym mail exploder.
exploitable channel 1. [A] Channel that allows the violation of the security policy governing an information system (IS) and is usable or detectable by subjects external to…
exposed facilities Any outside plant facilities subject to the effects of lightning; or to power contacts, power induction, or differences in ground potential any of which…
exposure Contact of an organism with a chemical, radiological, or physical agent.
express orderwire A permanently connected voice circuit between selected stations for technical control purposes.
extended ACL An optional directory access control feature available for an IBM® Lotus® Domino™ Directory and Extended Directory Catalog used to apply restrictions…
extended area service (EAS) A network-provided service feature in which a user pays a higher flat rate to obtain wider geographical coverage without paying per-call charges for calls…
extended binary coded decimal interchange code See EBCDIC.
extended superframe (ESF) In T-carrier, a synchronization frame that delineates 24 DS1 frames Note: ESF requires less frequent synchronization than the T-carrier D-4 superframe…
extended-definition television (EDTV) Television in which (a) improvements are made to the standard National Television System Committee (NTSC) television system, (b) the improvements are…
extensibility A property of a system, format, or standard that allows changes in performance or format within a common framework, while retaining partial or complete…
Extensible Markup Language See XML.
extension bell In telephony, a user end device, separate from a subscriber telephone, which device produces an audible signal indicating that there is an incoming call…
extension bit The first bit of each octet of the address field of a packet. The first octet is identified by the extension bit set to 0, and the second octet is…
extension facility A facility that provides access to communications for a user or group of users isolated from a central communications node.
extension terminal A terminal that is added to an existing terminal and that uses the same circuit and address, i.e., port and number, as the terminal to which it is added.
external environment A set of external entities to the application platform with which information is exchanged.
external environment interface (EEI) The interface between the application platform and the external environment across which information is exchanged.
external timing reference In a given communications system, a timing reference obtained from a source, such as a navigation system, external to the given system.
external viewer A plug-in, add-on, or helper application used with a Web browser to present graphics, audio, or video files.
extinction coefficient The sum of the absorption coefficient and the scattering coefficient. [From Weik '89]
extinction ratio (re) The ratio of two optical power levels, of a digital signal generated by an optical source, e.g.
extra bit Synonym added bit.
extra block Synonym added block.
extra sector In information assurance, a sector that is written on a diskette track in excess of the standard number of sectors, as part of a method of copy protection.
extra track In information assurance, a track that is written on a diskette in excess of the standard number of tracks, as part of a method of copy protection.
extraction resistance [The] capability of crypto-equipment or secure telecommunications equipment to resist efforts to extract [the] key. [INFOSEC-99]
extranet An Internet based access method to a corporate intranet site by limited or total access through a security firewall.